quack-twn/data/scripts/vector3.lua

local Vector3 = {
  x = 0,
  y = 0,
  z = 0,

  _CLASS_ = "Vector3"
}

setmetatable(Vector3, Vector3)

local function is_weak_vector3(t)
  if type(t) ~= "table" then return false end

  local haskeys = t.x ~= nil and t.y ~= nil and t.z ~= nil
  if not haskeys then
    return type(t[1]) == "number" and type(t[2]) == "number" and type(t[3]) == "number"
  else
    return type(t.x) == "number" and type(t.y) == "number" and type(t.z) == "number"
  end
end

function Vector3:__mul(b)
  if type(b) == "number" then
    return Vector3{
      x = self.x * b,
      y = self.y * b,
      z = self.z * b,
    }
  elseif type(b) == "table" and is_weak_vector3(b) then
    local other = Vector3(b)
    return Vector3{
      self.x * other.x,
      self.y * other.y,
      self.z * other.z,
    }
  end

  error("Vector3: other must be either a number or a Vector3-like table.")
  return Vector3()
end

function Vector3:__div(b)
  if type(b) == "number" then
    return Vector3{
      x = self.x / b,
      y = self.y / b,
      z = self.z / b,
    }
  elseif type(b) == "table" and is_weak_vector3(b) then
    local other = Vector3(b)
    return Vector3{
      self.x / other.x,
      self.y / other.y,
      self.z / other.z,
    }
  end

  error("Vector3: other must be either a number or a Vector3-like table.")
  return Vector3()
end

function Vector3:__add(b)
  if not is_weak_vector3(b) then
    error("Vector3: other must be a Vector3-like table.")
    return self
  end
  local other = Vector3(b)
  return Vector3{
    self.x + other.x,
    self.y + other.y,
    self.z + other.z,
  }
end

function Vector3:__sub(b)
  if not is_weak_vector3(b) then
    error("Vector3: other must be a Vector3-like table.")
    return self
  end
  local other = Vector3(b)
  return Vector3{
    self.x - other.x,
    self.y - other.y,
    self.z - other.z,
  }
end

function Vector3:__unm()
  return Vector3{
    -self.x,
    -self.y,
    -self.z,
  }
end

function Vector3:__call(...)
  local args = {...}
  local nv = {x = 0, y = 0, z = 0}
  setmetatable(nv, Vector3)
  if type(args[1]) == "number" then
    if #args == 1 then
      nv.x, nv.y, nv.z = args[1], args[1], args[1]
    else
      nv.x, nv.y, nv.z = args[1], args[2], args[3]
    end
  elseif type(args[1]) == "table" then
    if args[1].x ~= nil then
      nv.x, nv.y, nv.z = args[1].x, args[1].y, args[1].z
    else
      nv.x, nv.y, nv.z = args[1][1], args[1][2], args[1][3]
    end
  end
  return nv
end

function Vector3:__tostring()
  return "Vector3(" .. tostring(self.x) .. ", " .. tostring(self.y) .. ", " .. tostring(self.z) .. ")"
end

Vector3.__index = Vector3


--------API--------
function Vector3:length_squared()
  local x2 = self.x * self.x
  local y2 = self.y * self.y
  local z2 = self.z * self.z

  return x2 + y2 + z2
end

function Vector3:length()
  return math.sqrt(self:length_squared())
end

function Vector3:normalized()
  local length = math.sqrt(self:length_squared())
  if length == 0 then
    return Vector3()
  end
  return Vector3(self.x / length, self.y / length, self.z / length)
end

function Vector3:dot(with)
  if not is_weak_vector3(with) then
    error("Vector3: with must be a Vector3-like table. Returning 0")
    return 0
  end

  local v2 = Vector3(with)
  return self.x * v2.x + self.y * v2.y + self.z * v2.z
end

function Vector3:cross(with)
  if not is_weak_vector3(with) then
    error("Vector3: with must be a Vector3-like table. Returning Vector3()")
    return Vector3()
  end
  local v2 = Vector3(with)
  return Vector3 {
    self.y * v2.z - self.z * v2.y,
    self.z * v2.x - self.x * v2.z,
    self.x * v2.y - self.y * v2.x,
  }
end

---- CONSTANTS

Vector3.UP = Vector3(0, 1, 0)
Vector3.DOWN = -Vector3.UP
Vector3.FORWARD = Vector3(0, 0, -1)
Vector3.BACK = -Vector3.FORWARD
Vector3.RIGHT = Vector3(1, 0, 0)
Vector3.LEFT = -Vector3.RIGHT

-------------------
return Vector3